What Is an Abiotic Factor?

Nonliving aspects of an ecosystem that impact the species who live there are called abiotic factors. Temperature, sunlight, water, salinity and soil are all prominent examples. While not actually biological in nature, abiotic factors are highly relevant to ecology, the field of biology that studies how species interact with each other and with their shared environment.

Temperature

Temperature is often crucial in determining which species can inhabit a given ecosystem. At low temperatures, the proteins in your cells and those of other organisms can lose their structure so they no longer perform their functions. At even lower temperatures, water freezes and bursts cells. Chemical reactions and processes inside cells are temperature-sensitive, so most organisms are optimized to thrive within a certain temperature range. That temperature range can be very different for different species. The Antarctic icefish, for example, spends its life in waters with temperatures below 32 degrees Fahrenheit.

Water and Salinity

All life on Earth needs water. The abundance and quality of water in an ecosystem is another important abiotic factor that determines which species can live in an environment. A tree from the rainforest wouldn't last long if transplanted to the desert, for example, but cacti have evolved special adaptations to deal with desert life. A problem related to water abundance is salinity. Some environments like seawater are high in salt, so species that live there must be adapted to these conditions. Species that live in freshwater environments need other adaptations.

Sunlight

All plants and photosynthesizing bacteria or algae need sunlight. In some places sunlight is abundant, in others more limited. Every meter (roughly 3 1/3 feet) of seawater absorbs about 45 percent of red light and 2 percent of blue light that passes through. In the ocean, then, availability of light or lack of it is an important abiotic factor that helps determine how plentiful algae are at different depths. Since algae are at the base of most ocean food chains, this consideration matters for all other ocean life as well.

Soil

The pH and composition of soil is an important abiotic factor for plant growth. Different species of plants have become adapted to many kinds of soils. Ultimately, however, they all share certain basic requirements. Without soil nutrients, plants cannot grow. If the pH is too high or too low, this also ensures their demise. Bacteria and fungi are microscopic but essential contributors to soil fertility, so soil is an example of a situation where one group of organisms help shape an abiotic factor affecting another group of organisms.